Electrical instrument



Nov. 2, 1937. H. DALLMANN ELEC'I'RIG'AL INSTRUMENT Inventar:

Herbertgli)gl Im nn,

Filed Jan. 25, 1934 Attor*ney.

Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE ELEC'IRICAL INSTRUMENT Herbert Dallmann,

Karlshorst,

Germany, as-

signor to General Electric Company, a corporation 01 New York 1 Claim.

My invention relates to electrical instruments anti concerns particularly ratio instruments and receivers for telemetering' systems of the ratio type.

II; is an object of my invention to produce a ratio indicator in which a relatively large angle scale may be employed if desired exceeding 360, It is another object of my invention produce a ratio instrumeno from which a large torque may be obtained. A further object of my invention 1s to produce a high torque, large angle receiver for telemetering systems and lt is still another object of my invention to provicle a telemetering system in Which independent indicating and integrating apparatus may be employed wlthout; one type 0f apparatus aflecting the operation of the other. Other anal further objects and advantages will become apparent as the description proceeds.

In accordance With my invention in its preferred fcrm, I utilize the compensation principle in order cause the adjustrnent of one er both of two opposing elements subjected to the cu1= rents er voltages 130 be compared so that unhalance in the elements efiects a variation in the adjustmeni; until a balance is obtained.

The features, of my invention, which I believe to be novel and patentable, will be pointed out in the claim appended hereto. A better understanding o1 my invention, itself, however, may be obtained by referring to the following descripbion haken in connection with the accompanying drawing in. which Fig. 1 is a diagram representing a resistance type f receiver for telemetering systems in which the magnitude of the quantity (so be transmltted determines the ratio 0f two transmitted currents or voltages; Fig. 2 is a diagramma.tic side view illustrating another embodiment of my invention in which the currents to be compared actuate opposing elements cooper- Ming wlth a movable armature; Fig. 3 is a. diagram representing a modified form of the ernbodiment of Fig. 2, and Fig. 4 is a. partial diagram of. the arrangement of Fig. 2 presenting a plan view of the movable armature and representing two difierent positions of one of the opposir;g elements.

Referrlng now more in detall 130 the drawing in whlch like reference charact.ers are u.sed to designate like parts tloughout, in the arrangement shown in Fig. 1, the currents to be compared, which may be either alternating or direct currents, are supplied to the apparatus through terminals II, I2, and I3. I1 the apparatus is used as the reoeiver of a telemetering system. ehe

system will, obviously, be lndependent cf variations in the strength of the current source slnce she indications depend upon ths ratio rather than upon the strength of the currents or of the voll:- ages of the System.

A resistor I4 is -connected between the terminals II anal I2 and a resistor I5 ls connected between the terminals I2 anal I3. A rheostat I6. having a, movable contact arm I7, is connected in parallel with one of the resistors, for example, the resistor HI, in order to vary the current Flowing through the resistor I4 for the purpose of compensation. Resistors I4 and I5 preferably have tne same resistance laut, if deslred, may also be arranged to have different; reslstances having a fixed relationshlp to each other. A suitable current responsive device I8 for producing rotary motion in response 130 current 1s cannected beween the terminals II and I3. The type of current responslve device I8 to be employed depends an the character oi the telemeterapparatus.

In the case of a direct current system, the

'connections are such that the currents enter through two 0f the terminals II and I3 and leave by the common terminal I2 o1 vice Versa. 'I'he terminals II and I3 will then ea.ch carry one of the currents t0 be comparecl and the terminal I2 Will carry the sum 01 the currents. 'Ihis arrangement, therefore, permits the use of a threewire transmission system or a, two-wire transmission system and a ground, for connecting the transmitting and recelving statlons of a. telemetering system. The rotatable current responsive element I8 is arranged 120 co'ntrol the position of the movable arm IT. II deslred, the element I8 may be connected the movable arm I7 of the rheostat I6 by suitable means'such as reduction gearing, belting, linkages, or may also be directly connected by rneans 015 a shaft I9, as illustrated for the sake of simpliclty, since the palrticular means for causing the current responsive elemenl: I8 to control the posltion of the movable contact arm I1 does not form a. part o! my lnventlon.

'Ihe connections are such that, when a current flows in the element M, it tends to move the contact arm 611 in the direction required to cause such .a, relative varlation in the currents in the resistors M and H2 that current ceases toflow in the element H2 and the contact arm H comes to rest in a position which, obviously, depexids upon the ratio of the currents supplied at terminals M and l2 ancl, therefore, serves as an indlcation of this ratio. If the resistors; M and. 655 have: the same resistance, the position of balance will obviously correspond to'that in which resistors M and H5 carry equal curren-ts so that the voltage drops therein will be equal and the potential difference between the terminals l|ll and l2 Will be zero. But, as will be readily umlerstood 'by those skilled in the art, regardless of the relative resistance of the resistors M and l, there Will be a. predeterminecl relationship between the currents therein for which the voltage clr0ps will be equal, and the potential difference between'termlnals M ancl 83 and, canseq'uently, thecurrent inelement w will be zero. If the ratio between the received currents varies so that a pcwtential diflerence occurs between the terminab H andl H2, current Will flow in the element fl2 and the.oontact arm l'l will be rotated in the direction required to balance the appara- "aus.

The cur'lent received thmugh terminal E f], obviously, divides into two branches, one flowing directly through resistor M to terminal E2, ancl the other flowing from terminal M through canductor 22, stationary ring contact 2 l ccmtact arm W, resistor Iltll, conductor 22, back to terminal l2. If the apparatus is unbalanced, there Will also be a oomponent of current fiowing through the element 62 between terminals M and l2, which will cause a mtation cf the arm W, variatian of th.e resistance of resistor MB, and the redivision between the branches of the current fiawing in resistor M and rheostat ll@ until the voltage drops in resistors M! and l2 become equal and t.he locating arm Il'l comes to rest.

In the arrangement lllustraxterl schematically in Fig.- 2, the currents to be .comparecl are suppliec'l through two pairs of concluctors 23 and 22 elements 25 and 22 which cooperate wlth a rctartable element or armature 21V. lt will be understood that, lf desired, in the arrangement of Fig. 2, one of the conoluctors of each cf the conductor pairs 22 and 22 may be connectedl to a common comiuctor or ground in order to permit using the apparatus in a three-wire, or a, two-wire and grounrl system. 'Ihe elements 22 and 22 may tal:e any deslred. form depending an the character of the current energlzing the system. Fbr example, in the case of alternatingpleces 22' and 22' provided wlth shading coils 22 and 22 which cause a ratating er a shiftlng magnetlc field to be producecl by each 02 the elements 25 ancl 22 in accordance Wlth the well known principle of the induction type 02 meters ancl Instruments used With alternating currents. 'Ihe armature 217 may then take the form 02 a rotatable disc whicl1 is acted upon by the rotatlng fields produced by the elements 25 ancl 22 and the arrangement is such that the fielcl proclucewl lby element 25tends to produce rota tl0l1 o1 disc 22 in one direction ancl the field productd by element 26 tends to cause a rotation in the opposite dlrecrm.

Suitable means are provided. for causing the strength of the reaction between 0ne or both 02 the elements 25 anti 22 and the disc 22 to vary in response tqrotation 02 the disc 2'l. This may be accomplishecl by either mechanical or electrical means. One arrangement for accompllsh- Ing the result mechanically is shown by way of illustration in Fig. Z. For example the fielcl producing element 22 may be mountecl in a pivoted support er cradle 22 connected by means of gearing 5M 'to the shaft 32 of the rotating disc 2'l so that, as the disc 21 rotates, the element 22 is revolved so as to change i ts radial distance from the shaft 22 of the di sc 2ll, and; also 120 change the angular relationship between the shadlng coi1 22 and a radius cf the dlsc 2'l. F01 example, if the element 22 is swung inward toward the shaft the moment arm of the element 22 abou t the straft 32 is reducecl, therelqy dlminish ing the torque produced byelement 22. Likewise the line 2 ll' (See F1lg. 4) jolning the center of the polepiece' 22' of the element 22 am]. the

center of the shading coil 22 becomes lass nearly perpendicular to the raxfillus 2'l' 02 the disc 2'l extending toward the element 22. In Fig. 2 the induction disk 22 is shown as seen from above and the polepiece '26 is representecl in two dJf-' ferex1t positions, the full llne representatlon of the pole 22' in the posltion A corresponcls to the position shown in Fig. 2 and the dottegl llne representation in the position B illustrates the efiect of revolving the element 22 along the am C. The parts of the polepiece 22 in the posit1on A are designated by the same reference numerals as in Fig. 2, and in position B they are designated by porrespo'nding reference numerals wlth the-sux b. It will be understcod by those skilled in the art that the force procluced bx tlhe element 212 acts along tl1e llne 22' between the centers of the poleplece 26' 02 element 22 and the shading coil 22, whereas .a force tendlng to produce rotation of disc 271 must act along a; perpendicular to the radius 2'll cf dlsc 22 thr0ugh the point of application 02 the force. In the position B, the line 24l'b between the centers of the polepiece 2b and shading coll 22b ls nearly in llne With the raclius 2l'b. Consequently swinging the element 22 inward. re'cluces lts torque also by reduclng the component 02 f0rce perpendlcular to a radius of the dlsc 217. It will be observecl that the efiects of varlation in radial distance and 02 varlatlon in angularlty of element 22 are cumulatlve. The arrangement will obvi ously be such that the variatlon in the eifect prodnced lby the movement of the element 26 will loe such as to bring theelements 22 and 28 into balanceand cause the dlsc 2'l to come to rast in an angular positlon depenc'lent upon the relative strengths cf the currents er tl1e voltages supplied through tl'1e conductors 23 andl 24.

An electrical method for vary'ing the strength of the reaction between the element 26 andl the disc 217 1s disclosed in Fig. 3. In thls arran'gement the wincling 33 02 the element 26 is shunted by means of a rheostat 34 having a movable contact arm 35 whlch is .mechanlcally connected loy means of a belt 35 ancl the warm gearlng 3l to the shaft 22 of the ro tatable dlsc 2'H. F01 convenlence in making readings, a polnter or indlcator 31 may be mechanically c0nnected to the movable arm 35 so as to cooperate with a scale 32.

'lf'he operation of the apparatus shown in Fix. 3 will be readily understood from the drawlng and frorn the. explanation cf the apparatus disclqseol in Figs. 1 and. 2. When the current in the windlng 33 ls such thab the elements 25 and 26 are unbalanced the d1sc 21 1s caused to rotate in one directlon or another until the resistance 013 the rheostat 34 is sufilciently varied so that the division of current between wlndlng 33 anal rheostat 34 and consequently the eurrent in windlng 33 is such that the forces produced by elements 25 and 26 are balanced and the pointer 31 comes to rest In a position dependent upon the ratio ofthe current s or voll;- ages supplied to .conductors 23 and M.

II deslred, ratio lndicators 01 telemetrlc recelvers constructed in accordance with my invention may also be used in conjunction with integrating meters or other devices, as shown in Fig. 3. In this arrangement, the induotion type torque produclng elements 39 und. 4,!1 are connected in serles with the elements 25 and 26 respectlvely, and react with a revolving d1sc II counected through gearing 42 to a register I3. 'I'he rate of rota.tion of d1sc ll depends upon the skilled in the a.rt that many modiflcatlons and variatlons are Pos.sl ble and I a1m therefore to cover all such modiflcations and variattons as fa11 wlthin the scope 01 rpy inventiori, which 1s defined in the appended clalm.

What I claim as new and deslre to secure by Letters Patent cf the United Staates, ls: Apparatus responsive to the ratio between vtwo currents comprising a rotatable element composed o! current conducting material, a devioe actuated by one of said currents for producing a resultant shifting magnetic fie1d acting upon sald element, a second device actuated by the other of said currents and acting in opposition to said first mentioned device for producing a sec0nd resultant shifting magnetic field also acting upon said element, a rheostat connected in parallel to said second mentioned device divert an ad-- justable portion of cur1zent therefrom, and having a resistance adjustlng member mechanically connected to said rotatabl e element the counection being such that rotation of said rotatable element varies the reslstance of said rheostat in a direction required to dlvert .a suflicient portion of current; from said second flefd producing device to balance the eflfects o f satd fie1d producing devices on said rotatable element, whereby the po sition assumed by sa1d eleme nt provldes an indication of the ratio between'said currents.

HERBERT DAILMANN. 

